The SI unit for the amount of substance present is the mole.
The mole is defined as the amount of substance that has the same amount of particles as there are atoms in 12 grams of carbon-12. Mathematically, the moles of a substance may be computed using:
moles present = mass of substance / molecular mass of substance
![m=m_{0}*(\frac{1}{2})^{\frac{60}{30}}\\\\ m=m_{0}*(\frac{1}{2})^{2}\\\\ m=\frac{1}{4}m_{0}](https://tex.z-dn.net/?f=m%3Dm_%7B0%7D%2A%28%5Cfrac%7B1%7D%7B2%7D%29%5E%7B%5Cfrac%7B60%7D%7B30%7D%7D%5C%5C%5C%5C%0Am%3Dm_%7B0%7D%2A%28%5Cfrac%7B1%7D%7B2%7D%29%5E%7B2%7D%5C%5C%5C%5C%0Am%3D%5Cfrac%7B1%7D%7B4%7Dm_%7B0%7D)
If the half-life of a sample of a radioactive substance is 30 seconds, how much would be left after 60 seconds? <span>
A. one-fourth</span>
Molarity is expressed as
the number of moles of solute per volume of the solution. The mass of oxalic acid dihydrate needed for the solution is calculated as follows:
Amount in moles: (0.357 mol H2C2O4•2H2O / L) (.250 L ) = 0.0893 mol H2C2O4•2H2O
Amount in mass : 0.0893 mol H2C2O4•2H2O (126.08 g / mol ) = 11.2589 g H2C2O4•2H2O
Hope this answers the question. Have a nice day.
Answer:
Specific heat of metal of the metal is 0.8394J/g°C
Explanation:
The heat the water gain is the same losing for the metal. The equation is:
m(Metal)*ΔT(Metal)*S(Metal) = m(Water)*ΔT(Water)*S(Water)
<em>Where m is mass: 66.0g water and 28.5g Metal</em>
<em>ΔT is change in temperature: (95.25°C-27.84°C) = 67.41°C for the metal and (27.84°C - 22.00°C) = 5.84°C for the water</em>
<em>And S is specific heat of water (4.184J/g°C) and the metal</em>
<em />
Replacing:
28.5g*67.41°C*S(Metal) = 66.0g*5.84°C*4.184J/g°C
S(Metal) = 0.8394J/g°C
<h3>Specific heat of metal of the metal is 0.8394J/g°C</h3>
<em />
Answer:
<h3>2. A</h3><h3>7. C</h3><h3>8. A</h3><h3>9. D</h3><h3>10. D</h3>
Explanation:
I HOPE IT HELPS :)